The present disclosure relates generally to a fault detection system. Fault detection systems protect power electronics from faults conditions caused by power source disruptions, poor power quality of incoming power, and power electronic component failure. Existing fault detection systems suffer from a number of shortcomings and disadvantages. There remain unmet needs including improving response time, reducing system complexity, and increasing sensitivity and selectivity to faults. For instance, certain fault detection systems protecting motor drives with an input transformer require numerous sensors on the primary winding and secondary windings of the transformer. Detecting a fault requires inputs from each of the sensors, which increase costs and complexity of the detection scheme. Therefore, there is a significant need for the unique apparatuses, methods, systems and techniques disclosed herein.